Unless otherwise indicated herein, the materials described, in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Ubiquitous computing (ubicomp) depends heavily on wireless networking technology to support the automatic participation of many everyday objects in a computing environment. Example solutions for wireless communications for networks of ubicomp devices include wireless local area network (WLAN) technology or wireless personal area network (WPAN) technology. Related network solutions may include BLUETOOTH, ZIGBEE, WIRELESSHART, WI-FI, Mill and various other wireless communication solutions and technologies promulgated by the IEEE 802 working groups.
A wireless ubicomp network may have many devices participating in the network. For example, a ZIGBEE network implemented in a home may have hundreds of connected devices, including light switches, outlets, thermostats, appliances, remote controls, motion sensors, security sensors, controllers, coordinating devices, and the like. Many of these devices may be connected to a fixed power supply, while others may operate on battery power. In addition, some of the devices, such as light switches, outlets, and thermostats, may be fixed at a particular location, while others, such as remote controls and key fobs, may be “mobile” and move throughout the home.
A device in the ubicomp network may communicate directly with other devices within range of the wireless transmissions. In addition, some devices may forward or repeat transmissions to other devices within range, allowing a tree or mesh networking topology to be constructed. A device in the network may discover the other devices within range by broadcasting an introductory beacon, typically during a designated beacon period. The device may then listen for responses to the introductory beacon and exchange information with the responding devices, such as the identity of the network, the type of the responding device, other remote devices reachable through a responding device, and the like.
While it may take significant energy to engage in this device discovery process, the process is typically only performed on the occasion of a new device being added to the wireless ubicomp network. However, a mobile device moving through the physical topology of the network may cause a cascade of device discovery processes, as the mobile device moves out-of-range of one set of devices on the network and in-range of a new set of devices. This repetition of the discovery process may be compounded in WPAN ubicomp networks, such as a ZIGBEE network, that have significantly smaller wireless communication range, often in the single-digit meters. The repetition of the discovery process in a short-range wireless network with high mobility devices can lead to network congestion and increased power usage, dramatically reducing the operational life of battery-powered devices in the network.